Custom Search
Over 10000 Pages Indexed
Your Host
Click here to read about RF CafeKirt
Blattenberger

... single-
handedly
redefining
what an
engineering website
should be.

View the YouTube RF Cafe Intro Video Carpe Diem!
(Seize the Day!)

5CCG (5th MOB):
My USAF radar shop

Hobby & Fun

Airplanes and Rockets:
My personal hobby website

Equine Kingdom:
My daughter Sally's horse
riding business website -
lots of info

•−•  ••−•    −•−•  •−  ••−•  •
RF Cafe Morse Code >Hear It<

Job Board

About RF Cafe©

RF Cafe E-Mail

Re: GSM mobile phone - RF Cafe Forums

Because of the high maintenance needed to monitor and filter spammers from the RF Cafe Forums, I decided that it would be best to just archive the pages to make all the good information posted in the past available for review. It is unfortunate that the scumbags of the world ruin an otherwise useful venue for people wanting to exchanged useful ideas and views. It seems that the more formal social media like Facebook pretty much dominate this kind of venue anymore anyway, so if you would like to post something on RF Cafe's Facebook page, please do.

Below are all of the forum threads, including all the responses to the original posts.


 Post subject: Re: GSM mobile phone
Posted: Fri Feb 26, 2010 12:18 pm 
 
Captain

Joined: Sat Mar 04, 2006 10:12 am
Posts: 11
The main two differences between any of the telecom standards are the frequency bands of operation and the modulation techniques. Some use frequency modulation, others use phase modulation, but all are some form of digital modulation. Just as there are disparate groups of auto enthusiasts that fervently believe their choice of car is the best, groups exist in the mobile communications cadres that think theirs is the best. Some systems are better than other form the standpoint of bandwidth efficiency, but that often comes with a degradation in call quality - particularly in weak signal conditions.

Take for example 16-QAM, where the receiver must correctly discern 16 unique phase angle/amplitude combinations to properly decode a data package. With a strong signal and a slow-moving platform (a walking talker), a phone can usually get near 100% of the data packages without the need for error correction or maybe have to request that the packet be re-sent from the tower. Same goes in the other direction from talker to tower.

Wne a user is moving quickly in a low power enviroment with lots of signal interferes around (electronics and physical), the system often breaks down. That is because of ambiguity in phase, amplitude. Take a simple BPSK signal in the same environment that only needs to discern between two separate states and it has a much better chance of surviving. Problem is, though, is that BPSK takes 8x the BW of a 16-PSK signal.

You can look up the technical difference between the various mobil phone systems, but in a nutshell this is the difference.




Posted  11/12/2012
A Disruptive Web Presence

Custom Search
Over 10,000 pages indexed! (none duped or pirated)

Read About RF Cafe
Webmaster: Kirt Blattenberger
    KB3UON

RF Cafe Software

RF Cascade Workbook
RF Cascade Workbook is a very extensive system cascaded component Excel workbook that includes the standard Gain, NF, IP2, IP3, Psat calculations, input & output VSWR, noise BW, min/max tolerance, DC power cauculations, graphing of all RF parameters, and has a graphical block diagram tool. An extensive User's Guide is also included. - Only $35.
RF system analysis including
frequency conversion & filters

RF & EE Symbols Word
RF Stencils for Visio

Product & Service Directory
Personally Selected Manufacturers
RF Cafe T-Shirts & Mugs

RF Cafe Software

Calculator Workbook
RF Workbench
Smith Chart™ for Visio
Smith Chart™ for Excel